This invention relates generally to gas turbine engines and, more particularly, to apparatus for scavenging lubricating oil from the structure of a bearing during all operating conditions.
Gas turbine engines typically include a core engine having a compressor for compressing air entering the core engine, a combustor where fuel is mixed with the compressed air and then burned to create a high energy gas stream, and a first or high pressure turbine which extracts energy from the gas stream to drive the compressor. In aircraft turbofan engines, a second turbine or low pressure turbine located downstream from the high pressure turbine extracts more energy from the gas stream for driving a fan. The fan provides the main propulsive thrust generated by the engine.
Typically, a rotor shaft is supported within a non-rotating stator by bearings used in the turbine engine to accurately locate and rotatably mount the rotor with respect to the stator. The bearings are typically surrounded by oil sumps which contain lubricating oil which is sprayed onto the bearings. The bearing and sump are isolated from the hot gas path by a seal which prevents oil leakage from the sump and hot gas entry into the sump. The seal is a contact seal, typically a non-metallic brush seal or carbon seal. At low power points in the operation of the engine, lubricating oil tends to seep toward the seal. Any oil accumulation near the contact seal can cause coking or the creation of varnish on the seal surfaces, which can cause deterioration of seal performance.